For most workflows, GPT-6 Astra is the stronger default — openai's frontier answer to fable 5.1 — computer-use and agentic-coding leader at $10/$50.
The shortest way to see the safest default, the lower-cost option, and the specialist pick before you read deeper.
GPT-6 Astra is the safest overall answer here when you want the strongest default instead of the lowest list price.
Grok 4.5 is the lower-cost option to start with when you still need useful output at scale.
Claude Mythos 5.1 is the better pick when response speed matters more than maximum reasoning depth.
GPT-6 Astra leads on coding with a score of 100 vs 100 for Claude Mythos 5.1.
GPT-6 Astra has the larger context window: 1.05M vs 1M for Claude Mythos 5.1.
Both models are similarly priced — the decision comes down to capability, not cost.
GPT-6 Astra is the safer default: it is built for computer and browser use, long-horizon agentic coding, and frontier math and science work, which covers most of what people bring to this comparison.
Switch to Claude Mythos 5.1 when your work is mostly vetted frontier cybersecurity and life-sciences research at the absolute capability ceiling; on that narrower brief it is the better tool.
Both models serve different primary workflows — GPT-6 Astra for computer and browser use and long-horizon agentic coding, Claude Mythos 5.1 for vetted frontier cybersecurity and life-sciences research at the absolute capability ceiling — so running each where it has a clear edge often beats forcing one to do both.
Switch the scoring lens to see whether the top answer changes when you care more about cost, speed, or long-document work.
OpenAI / Premium / Sep 4, 2026
OpenAI's frontier answer to Fable 5.1 — computer-use and agentic-coding leader at $10/$50.
Ranks models by the broadest mix of coding, writing, research, and long-context usefulness.
You are cost-sensitive or latency-bound — GPT-5.6 Sol is a fifth of the price — or you need it today in an Enterprise workspace, where it is off by default, or for offensive-security work, which it refuses outside OpenAI Daybreak.
The fastest way to see where the recommendation shifts when your priority changes.
OpenAI's frontier answer to Fable 5.1 — computer-use and agentic-coding leader at $10/$50.
Fable 5.1 with the safeguards lifted — partner-only, 60.9% Terminal-Bench 4.0.
Every figure below is the provider's list price or a published capability score — the same numbers the recommendation on this page is built from.
| Model | Input | Output | Est. month | Context | Speed | Coding | Writing | Research |
|---|---|---|---|---|---|---|---|---|
| GPT-6 AstraOpenAI | $10.00/1M | $50.00/1M | $200 | 1.1M tokens | Deliberate | 100 | 97 | 100 |
| Claude Mythos 5.1Anthropic | $10.00/1M | $50.00/1M | $200 | 1M tokens | Deliberate | 100 | 97 | 99 |
Capability scores are out of 100 and reflect our own weighting of published benchmarks and production signals — see how we evaluate models. “Est. month” assumes 10M input and 2M output tokens at list price, with no batch or caching discounts applied, so treat it as a ceiling.
What each one is genuinely good at, where it falls down, and the situations we would steer you away from it — not just the headline score.
OpenAI's September 3, 2026 frontier release — the first GPT-6 model and OpenAI's answer to Claude Fable 5.1 two days earlier. State of the art on computer use (OSWorld 2.0 72.6% in ~47% less time than GPT-5.6 Sol), agentic coding (Terminal-Bench 4.0 57.9%), and frontier math (FrontierMath Tier 4 97.6%). $10/$50 per 1M tokens, 1.05M context, 128K output, knowledge cutoff April 30, 2026.
You are cost-sensitive or latency-bound — GPT-5.6 Sol is a fifth of the price — or you need it today in an Enterprise workspace, where it is off by default, or for offensive-security work, which it refuses outside OpenAI Daybreak.
The new computer-use and agentic-coding ceiling, and OpenAI's first model priced like a Mythos-class Claude. Astra beats Claude Fable 5.1 on Terminal-Bench 4.0 (57.9% vs 55.8%), Terminal-Bench Science (64.6% vs 52.6%) and FrontierMath Tier 4 (97.6% vs 87.8%), and it is the only model with a credible OSWorld 2.0 result above 70%. It loses to Fable 5.1 on Humanity's Last Exam and on Artificial Analysis's index, costs five times GPT-5.6 Sol, and ships without a SWE-bench number. If your work is computer use, browser agents or math, it is the pick; for everyday coding at scale, Sol at $2/$10 remains the value default.
Released September 3, 2026. API ID gpt-6-astra; rolling out over the coming days to ChatGPT Plus, Pro, Business and Enterprise (usage inside existing allowances; GPT-6 Astra Pro for Pro/Business/Enterprise; Enterprise off by default), the OpenAI API, Microsoft Azure and Amazon Bedrock. Standard API pricing $10/$50 per 1M tokens; Fast mode is up to 2x speed at 2x price; cache reads and writes have separate rates. Model docs list 1,050,000 context, 128,000 max output, knowledge cutoff April 30, 2026, reasoning efforts up to 'max'. Published launch numbers (Astra / GPT-5.6 Sol / Fable 5.1 / Opus 5): OSWorld 2.0 72.6 / 65.7 / — / 70.2; Terminal-Bench 4.0 57.9 / 37.3 / 55.8 / 52.3; Terminal-Bench Science 0.1 64.6 / 22.4 / 52.6 / 30.0; FrontierMath Tier 4 v2 97.6 / 83.0 / 87.8 / 73.2; GPQA Diamond 96.0 / 94.6 / 93.7 / 93.7; Humanity's Last Exam w/ tools 57.2 / — / 65.0 / 63.6; AutomationBench 41.4 / 18.1 / 31.4 / 26.9; DeepSWE v1.1 74.1 / 72.7 / 67.4 / 73.7; ARC-AGI-2 95.0 / 92.5 / 90.0 / 90.4; ARC-AGI-3 99.9 (OpenAI responses-API harness; ARC Prize's stateless runs score far lower) / 7.8 / — / 30.2; ExploitBench 100.0 / 78.5 / — / 70; SRE-Bench 88.0 / 55.9; Artificial Analysis Intelligence Index v4.1.1 61.2 / 60.9 / 65.7 / 63.1. Meets the Critical threshold for cybersecurity under OpenAI's Preparedness Framework; advanced cyber workflows gated behind OpenAI Daybreak. All figures from OpenAI's launch post and model docs, verified September 4, 2026.
The unrestricted twin of Claude Fable 5.1 — the same model with safeguards lifted in high-risk areas, released September 1, 2026 to vetted cybersecurity and life-sciences organisations under Anthropic's trusted-access programme. Scores 60.9% on Terminal-Bench 4.0, the highest agentic-coding result Anthropic has published.
You don't hold vetted trusted access, or your work never trips Fable 5.1's safeguards — the two models are otherwise identical.
The highest published agentic-coding score anywhere — 60.9% on Terminal-Bench 4.0 — but you almost certainly cannot get it. Mythos 5.1 is Fable 5.1 with safeguards lifted, gated to vetted cybersecurity and life-sciences organisations. Unless you hold trusted access and hit refusals that block real research, Fable 5.1 is the same model at the same price.
Released September 1, 2026 alongside Claude Fable 5.1, continuing the Mythos-class line that began with Project Glasswing's April 2026 private preview. Access is limited to vetted US cybersecurity and life-sciences professionals. Same underlying model, pricing, context window, and cache-read discount as Fable 5.1; the only published difference is the safeguard level and the resulting Terminal-Bench 4.0 score (60.9% vs 55.8%).
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GPT-6 Astra wins on more of the categories we score — coding, research, long context — so it is the better default of the two. Claude Mythos 5.1 is the better pick when your work is mostly vetted frontier cybersecurity and life-sciences research at the absolute capability ceiling. Neither is universally "better": GPT-6 Astra is aimed at computer and browser use and long-horizon agentic coding, Claude Mythos 5.1 at vetted frontier cybersecurity and life-sciences research at the absolute capability ceiling.
Both models are similarly priced at $10/1M input tokens. The decision should come down to capability, not cost.
GPT-6 Astra has the larger context window at 1.05M tokens vs Claude Mythos 5.1's 1M. For large document analysis, GPT-6 Astra is the stronger pick.
GPT-6 Astra and Claude Mythos 5.1 are similarly matched on coding. GPT-6 Astra is the overall coding leader in this directory at 100/100.
Both GPT-6 Astra and Claude Mythos 5.1 have similar speed profiles — rated deliberate. Neither will be the bottleneck if latency is your deciding factor.
$10/$50 per 1M — five times GPT-5.6 Sol's $2/$10 and the same premium as Claude Fable 5.1; Fast mode doubles it again. Trails Claude Fable 5.1 on Humanity's Last Exam with tools (57.2% vs 65.0%) and on the Artificial Analysis Intelligence Index (61.2 vs 65.7). OpenAI published no SWE-bench Verified or SWE-bench Pro figure at launch, so it does not appear on our SWE-bench leaderboard. Avoid it if you are cost-sensitive or latency-bound — GPT-5.6 Sol is a fifth of the price — or you need it today in an Enterprise workspace, where it is off by default, or for offensive-security work, which it refuses outside OpenAI Daybreak. That is the main case for looking at Claude Mythos 5.1 instead.
Not generally available — restricted to vetted US organisations under Project Glasswing. No advantage for ordinary work; Fable 5.1 is the same model at the same price for everyone else. Same deliberate, high-latency profile and premium pricing as Fable 5.1. Avoid it if you don't hold vetted trusted access, or your work never trips Fable 5.1's safeguards — the two models are otherwise identical. Against GPT-6 Astra specifically, the two are close enough on capability that price and speed decide it.
Take a moderate workload of 10M input and 2M output tokens a month. GPT-6 Astra runs $200.00 (at $10/1M in and $50/1M out); Claude Mythos 5.1 runs $200.00 (at $10/1M in and $50/1M out). The gap is small enough that price should not decide this one. Output tokens dominate the bill on both, so prompt length matters far less than response length.
Yes, and for most teams that beats picking one. A common split is GPT-6 Astra for computer and browser use and long-horizon agentic coding, with Claude Mythos 5.1 handling vetted frontier cybersecurity and life-sciences research at the absolute capability ceiling. Since GPT-6 Astra is both the stronger and the cheaper option here, a split mainly makes sense if Claude Mythos 5.1 covers a capability you specifically need.